Resin composition and member comprising said resin composition

ABSTRACT

It is an object of the present invention to provide a resin composition which has a low hardness, is favorable in high loss properties (vibration absorbing properties) and gas permeation resistance, is excellent in injection moldability, thereby enabling itself to be injection molded with stable dimensional accuracy, and which is particularly suitable for constituting an elastic member for an ink jet printer, an insulator for a recording medium drive, a gasket for an HDD and an impact absorbing material for an HDD. The above object has been achieved with a resin composition which comprises 100 parts by weight of a thermoplastic elastomer containing an isobutylenic block copolymer composed of isobutylenic polymer blocks and aromatic vinylic polymer blocks, and 1 to 50 parts by weight of a polyolefin resin.

TECHNICAL FIELD

[0001] The present invention relates to a resin composition which has alow hardness, is favorable in high loss properties (vibration absorbingproperties) and gas permeation resistance, and is excellent in injectionmoldability, thus enabling itself to be injection molded with stabledimensional accuracy.

[0002] The present invention also relates to an elastic member for anink jet printer, an ink tank and an ink jet printer, more particularly,to an elastic member which is used as sealing members for an ink tankvalve and an ink tank in the case of an ink tank to be employed for anink jet printer that records printed letters on a recording medium bysupplying a recording head with ink, also as a sealing member forpreventing ink from leaking through the recording head in the main bodyof an ink jet printer, which enables itself to be injection molded bymeans of two-color molding, and which is constituted of a materialexcellent in sealing properties and oil bleed properties; and at thesame time pertains to an ink tank and an ink jet printer each using theaforesaid elastic member.

[0003] The present invention further relates to an insulator for arecording medium drive, more particularly, to an insulator which isendowed with desired performances such as favorable high loss properties(vibration absorbing properties) and oil preservability, low hardness,low compression set and the like, and which is favorably used for thevibration absorption of a recording medium drive such as a CD (compactdisc), a CD-ROM, an optical disc and the like.

[0004] The present invention still further relates to a gasket which isused for an HDD (hard disc drive), which is favorable in gastihgtnessand resistance to penetration and permeation of substances, and which isminimized in the generation of harmful gases, and also to a gasket whichis integrated with a cover and is for an HDD in which the gasket usedfor the HDD and the cover is integrally molded.

[0005] The present invention furthermore relates to an impact absorbingmaterial for an HDD, more particularly, to an impact absorbing materialwhich is used for an HDD, and which is excellent in impact absorbingproperties and also is minimized in the amount of gas generation.

BACKGROUND ART

[0006] A thermoplastic resin is capable of being injection molded, andis employed in a variety of fields. In order that the resin may copewith requirement characteristics varying depending on the purpose ofuse, it is a prevailing practice that a plurality of resins are used incombination.

[0007] It is one example of the foregoing that a rubber based resin isadded to a thermoplastic resin to enhance the impact resistance thereof,and an attempt is made to use a thermoplastic elastomer composed of ablock copolymer as a rubber based resin.

[0008] There is available as the thermoplastic elastomer as mentionedabove, for instance, a thermoplastic elastomer composed of anisobutylenic block copolymer as disclosed in Japanese Patent ApplicationLaid-Open Nos. 301955/1996 (Hei-8) and 246733/1999 (Hei-11). However,the resin composition in which the above-mentioned thermoplasticelastomer was used has not been always satisfactory in aspects ofhardness, loss properties, gas permeation resistance, injectionmoldability and the like.

[0009] In addition, there are proposed an elastic member for an ink jetprinter, an insulator for a recording medium drive, a gasket for an HDDand an impact absorbing material for an HDD that are each constituted ofa resin composition wherein a thermoplastic elastomer is used. Theabove-proposed items, however, each involve a problem as describedhereunder.

[0010] In the first place, the elastic member for an ink jet printerwill be described. An ink jet printer has heretofore been equipped withan ink chamber which is filled in with ink, and an ink tank having anink supply portion which supplies a recording head portion with ink.Examples of the type of the ink tank include a constitution such thatink is supplied to a recording head which is stationary attached to acarriage via a tube which is arranged in a unit so that the ink tank isfreely attachable to and detachable from the unit, a constitution suchthat the ink tank is integrated with a recording head so that the inktank is freely attachable to and detachable from a carriage and the likeconstitution.

[0011] The configuration of supplying the recording head with ink issuch that water head difference is set on the recording head in theformer, whereas in the latter, a negative pressure source is provided onthe ink tank side.

[0012] There have been proposed in recent years, more ink tanks in theform of the latter from the aspects of miniaturization of a unit andease of maintenance work.

[0013] Any of these ink tanks for the ink jet printers is required to becapable of satisfactorily supplying the recording head with ink whichcounterbalances the amount of the ink discharged from the recording headat the time of recording and at the same time, to be free from inkleakage through a discharge port at the time of non-recording.

[0014] An example of the ink tank meeting with the above-mentionedrequirement is an ink tank which is integrated with a recording head inwhich a cartridge is freely attachable to and detachable from acarriage, and which is filled inside with an absorbing body (foam). Byfilling an absorbing body in an ink tank in such a manner, it is madepossible to preserve ink inside the ink tank by the capillary force ofthe absorbing body and thus maintain stable meniscus of ink at the inkdischarge portion of the recording head. It is necessary in this casethat the absorbing body be filled in almost whole of the ink tank. Thusby allowing the absorbing body to hold an amount of ink some whatsmaller than a maximum amount thereof that can be held by the absorbingbody, internal negative pressure is generated by taking advantage of thecapillary force. Accordingly, even in the case where there existsmechanical input such as vibration or thermal input such as temperaturevariation in the recording head or the ink tank, it is made possible tominimize ink leakage through a discharge port of the recording head or acommunicating portion of the ink tank to atmosphere and thereby to carryout stable ink preservation.

[0015] Nevertheless the system in which the ink tank inside is almostwholly filled with the absorbing body involves a problem that theinternal negative pressure is increased, accompanying the consumption ofthe ink, thereby increasing the amount of ink remaining in the ink tankwithout being supplied to the recording head, whereby the applicationefficiency is deteriorated.

[0016] In order to solve the above-described problem, there is proposedan ink cartridge which is used for an ink jet recording head and whichis constituted, for instance, such that the ink tank inside is separatedinto an ink reservoir and a hollow portion by the use of a wall equippedwith a communication hole on a lower portion, an umbrella check valve ismovably installed on the communication hole, the check valve is openedat the time of point when the ink pressure in the recording head islowered so that the ink in the ink reservoir is discharged in the hollowportion and supplied to the recording head {Japanese Patent ApplicationLaid-Open No. 231759/1987 (Sho-62)}.

[0017] Since there is no need to house an absorbing body in a cartridgeaccording to the above-mentioned constitution, substantial amount of theink housed in the ink tank can be increased. However, there is ingeneral a serious problem with an umbrella check valve in that itsoffset is too large to accurately regulate the ink feed rate to therecording head, thereby causing variation in the ink feed rate and alsodeterioration of printing quality.

[0018] On the other hand, since the ink reservoir and the recording headare completely interrupted in a state of the umbrella check valve beingclosed, in the case where the ink in the hollow portion isvolumetrically expanded by 2 to 5% approximately due to variation inenvironmental temperature, there is caused a problem that an increase inthe pressure in the hollow portion breaks a seal between the recordinghead and a connection port, thus causing ink leakage; and in a state ofthe ink tank being integrated with the recording head, there is caused aproblem that the ink tank pressure acting thereon as such makes itimpossible to maintain the negative pressure therebetween, thus causingink leakage through the recording head.

[0019] Moreover, the umbrella check valve involves such a problem thatpressure difference of several tens of water gauge pressure to be keptfor stable ink supply to the recording head, which is too low to closethe valve, brings about a fear that it is opened in response to the inkswinging action due to carriage movement and also deterioration inprinting stability.

[0020] In order to solve the problem with the ink tank equipped with theaforesaid umbrella check valve, an attempt is made, for instance, toemploy an ink tank valve which is located at the position where the inkchamber and the ink supply portion are separated from each other, ismoved by the pressure difference therebetween, and supplies the inkfilled in the ink chamber to the recording head {Japanese PatentApplication Laid-Open No. 174860/1996 (Hei-8)}.

[0021] By equipping the ink tank with the ink tank valve, it is possibleto surely supply the recording head with ink, while certainly respondingto slight pressure difference between the ink tank and the recordinghead without being influenced by the ink swinging action due to carriagemovement so as to maintain negative pressure well suited for printingand at the same time, it is enabled to prevent ink from leaking throughan ink supply port due to temperature variation and/or through therecording head.

[0022] There are usually used in the ink tank valve, an elastic materialexemplified by an elastic material adhesively bonded to a plasticsubstrate and the like, in which thermosetting rubber has heretoforebeen generally used as the elastic material. However the thermosettingrubber involves a problem of difficulty in injection molding bytwo-color molding with plastics, of a high production cost for theaforesaid valve and besides, of difficulty in molding and vulcanizing amember of a desirable shape by using a material having lowered hardness.

[0023] On the other hand, ink leakage from an ink tank for replacementhas hitherto been prevented by attaching a foamed elastic member such aspolyurethane foam thereto at an ink supply port, but a long-term usethereof makes it impossible to hold ink as the case maybe, wherebydevelopment of an elastic member excellent in durability has eagerlybeen desired.

[0024] In regard to the ink jet printer, in the case of a printer beingunactuated, the recording head is made to stand by at the end of themain body of the ink jet printer. In order to prevent ink from leakingthrough the recording head in the case of this standing by, therecording head is housed on a sealing member placed along a recessprovided on the main body of the ink jet printer. Thermosetting rubber,which is usually used as the sealing member, involves the problem sameas the foregoing.

[0025] As can be seen in Japanese Patent Application Laid-Open No.978/2000 (Hei-12), there is filed a patent application concerning anelastic member which is used for an ink jet printer and in which astyrenic elastomer is used. Examples of the styrenic elastomersdescribed in the patent gazette include SEPS, SEBS, SBS and SIS in whichsoft segment is polyethylene propylene, polyethylene butylene,polybutadiene or polyisoprene. As is well known as the information onrubber materials for general purpose use, these polymers are notnecessarily excellent in gas permeation or moisture permeation. Thus thepolymers, when being required of lower gas permeation performance orlower moisture permeation performance, sometimes results in failure tomanifest satisfactory performances.

[0026] Next, the insulator for a recording medium drive will bedescribed.

[0027] A drive for a recording medium wherein information is written insuch as a CD, CD-ROM and optical disc is equipped inside with arecording medium driving portion which records and/or reproduces therecording medium, and on which are mounted an electric motor for drivinga recording medium, a pickup means for recording and/or reproducing therecording medium and the like. The motor and/or pickup means are notresistant to vibration from outside and inside in an aspect ofmechanism, and hence are equipped with an insulator composed ofthermoplastic rubber or the like for the purpose of insulating thevibration.

[0028] As a construction material for the above-mentioned insulator fora recording medium drive, there have hitherto been used general purposerubber which is exemplified by silicone rubber and butyl rubber, andwhich has a hardness of about 20 to 50 degrees in terms of JIS Ahardness; a gel; an oil damper and the like.

[0029] The above-cited rubber material, which has a loss factor notsufficiently high, has frequently brought about a cause for malfunctionowing to high vibration transmission rate at around the resonancefrequency and insufficient vibration insulation upon writing in on arecording medium.

[0030] For these reasons, in the case of using a rubber material as avibration insulation material, the vibration insulation properties whichcould never been attained in a low frequently region have been achievedby devising the shape of the vibration insulation material, forinstance, by molding the material into an intricate shape through thinwall molding or the like.

[0031] Nevertheless, the thin wall causes deterioration of strength,liability to damage upon molding and thus difficulty in enhancingproductivity. Further in the case of vulcanized rubber, problems arecaused in that there is a concern that sulfur as a vulcanizing agentremains and influences electronic part items, and in that siliconerubber brings about possibility of contact trouble due to low molecularweight silicone.

[0032] For the purpose of achieving vibration insulation in a lowfrequently region, the use of a more soft material such as a gel istaken into consideration. However there is a concern that a low hardnessmaterial is liable to deformation due to compression, is deteriorated invibration insulation properties with the lapse of time, and allows lowmolecular weight components in the material to bleed out, therebyexerting adverse influence on a disc requiring vibration insulation.Next, the gasket for an HDD will be described.

[0033] In recent years, electronic equipment such as a computer has cometo have intricate circuit constitution, accompanying the progresstowards a high performance and compactification, and is prone to bereadily damaged even by a slight amount of dust. Accordingly, dustprevention is increasingly required in practical application, thusmaking it a usual practice to put a gasket on the junction surfacebetween a box type main body incorporating the electronic equipment anda cover thereof, tighten the body and cover, and integrate the same byhermetical sealing. Further in order to simplify the handling upon use,there is frequently used a cover integrated with a gasket in which acover and a gasket are integrated with each other.

[0034] However, owing to high densification of electronic part items, agasket and sealing member are increasingly required that are moreresistant to the permeation of dust and chemicals than conventionalproducts and at the same time, are free form the generation of harmfuloutgas, namely free from chemical contamination.

[0035] Next, the impact absorbing material for an HDD will be described.

[0036] An actuator for a hard disc drive (HDD) is a device which locatesthe position of a magnetic head installed at the tip of the actuatorwhich constitutes a part of a positioning mechanism for a high velocityhead, and besides, records and reproduces magnetic signals on themagnetic disc by means of the above-mentioned magnetic head. Thepositioning of the magnetic head is put into practice by controlling theLorentz force which is generated by a coil that is supported with avoice coil motor and an actuator through the control of electric currentto be passed through the aforesaid coil.

[0037] The actuator is equipped in the vicinity thereof with a stoppermechanism termed crush stop which is intended to prevent a magnetic headand/or a head gimbals assembly from colliding with another member,falling out or being damaged in the event that a head positioningmechanism becomes uncontrollable and runaway by reason of malfunctioningor the like.

[0038] There has heretofore been prevalently employed as theabove-mentioned impact absorbing material for an HDD, an elastic bodycomposed of a thermoplastic elastomer of any of polyurethane base andpolyvinyl chloride base. However, the impact absorbing material which isused for an HDD and made of the aforesaid elastic body has involved suchproblems as a large amount of harmful gas generation and insufficiencyfor use as a crush stop.

DISCLOSURE OF THE INVENTION

[0039] An object of the present invention is to provide the followingunder such circumstances.

[0040] (1) A resin composition which has a low hardness, is favorable inhighloss properties (vibration absorbing properties) and gas permeationresistance, and is excellent in injection moldability, thereby enablingitself to be injection molded with stable dimensional accuracy,

[0041] (2) An elastic member which is used for an ink jet printer, whichis favorably used in particular in an ink jet printer as an ink tankvalve that is installed at a position where an ink chamber and an inksupply portion are separated from each other, is moved by the pressuredifference therebetween, and supplies a recording head portion with inkfilled in the ink chamber, also as a sealing member that is installed atan ink supply port, and prevents ink from leaking through said port, oras a sealing member that is installed on the main body of the ink jetprinter, prevents ink from leaking through the recording head, andprevents the recording head from drying, which enables itself to beinjection molded by means of two-color molding, and which is constitutedof a material excellent in sealing properties and oil bleed properties;an ink tank; and an ink jet printer each using the aforesaid elasticmember.

[0042] (3) A gasket which is particularly well suited for use in an HDD(hard disc drive), which is favorable in gastihgtness and resistance topenetration and permeation of substances, and which is minimized in thegeneration of harmful gases, and also a gasket integrated with a cover.

[0043] (4) An insulator which is used for a recording medium drive,which is excellent in vibration absorption of lightweight articles,particularly in a low frequency region and in durability by virtue ofthe use of materials characterized by high loss properties(vibrationabsorbing properties), oil preservability, low hardness, low compressionset and the like.

[0044] (5) An impact absorbing material which is used for an HDD, whichhas sufficient impact absorbing properties and which is minimized in theamount of harmful gas generation.

[0045] As a result of intensive extensive research and investigationaccumulated by the present inventors in order to achieve theabove-mentioned objects, it has been found that said objects can beachieved by constituting the foregoing members and materials of a resincomposition in which a thermoplastic elastomer containing a specificblock copolymer is blended with a specific component. Thus the presentinvention has been accomplished on the basis of the foregoing findingsand information.

[0046] That is to say, the present invention provides the following.

[0047] 1. A resin composition which comprises 100 parts by weight of athermoplastic elastomer containing an isobutylenic block copolymercomposed of isobutylenic polymer blocks and aromatic vinylic polymerblocks, and 1 to 50 parts by weight of a polyolefin resin;

[0048] 2. An elastic member which is for an ink jet printer and which isconstituted of the resin composition as set forth in the preceding item1;

[0049] 3. An insulator which is for a recording medium drive and whichis constituted of the resin composition as set forth in the precedingitem 1;

[0050] 4. A gasket which is for an HDD and which is constituted of theresin composition as set forth in the preceding item 1;.

[0051] 5. An impact absorbing material which is for an HDD and which isconstituted of the resin composition as set forth in the preceding item1;

[0052] 6. The resin composition as set forth in the preceding item 1wherein an aromatic vinylic compound which constitutes the aromaticvinylic polymer blocks is at least one species selected from the groupconsisting of styrene, α-methylstyrene and p-methylstyrene;

[0053] 7. The resin composition as set forth in the preceding item 1wherein the ratio by weight of the isobutylenic polymer blocks in theisobutylenic block copolymer to the aromatic vinylic polymer blockstherein is in the range of 60:40 to 80:20;

[0054] 8. The resin composition as set forth in the preceding item 1wherein the polyolefin resin is isotactic polypropylene or a copolymerthereof;

[0055] 9. The resin composition as set forth in the preceding item 1wherein the polyolefin resin is modified polyolefin;

[0056] 10. The resin composition as set forth in the preceding item 1wherein the thermoplastic elastomer containing an isobutylenic blockcopolymer contains a thermoplastic elastomer other than said elastomerin addition to said isobutylenic block copolymer;

[0057] 11. The resin composition as set forth in the preceding item 1which further comprises at most 100 parts by weight of polyphenyleneether based on 100 parts by weight of the thermoplastic elastomercontaining an isobutylenic block copolymer composed of isobutylenicpolymer blocks and aromatic vinylic polymer blocks;

[0058] 12. The resin composition as set forth in the preceding item 1which further comprises at most 200 parts by weight of a non-aromaticsoftening agent for rubber based on 100 parts by weight of thethermoplastic elastomer containing an isobutylenic block copolymercomposed of isobutylenic polymer blocks and aromatic vinylic polymerblocks;

[0059] 13. The resin composition as set forth in the preceding item 1which further comprises 10 to 100 parts by weight of a petroleum basehydrocarbon resin based on 100 parts by weight of the thermoplasticelastomer containing an isobutylenic block copolymer composed ofisobutylenic polymer blocks and aromatic vinylic polymer blocks;

[0060] 14. The elastic member for an ink jet printer as set forth in thepreceding item 2 which is installed on the main body of said ink jetprinter, and is used as a sealing member;

[0061] 15. An ink tank which comprises the elastic member as set forthin the preceding item 2;

[0062] 16. An ink tank which comprises the elastic member as set forthin the preceding item 14;

[0063] 17. An ink jet printer which comprises the elastic member as setforth in the preceding item 2;

[0064]18. An ink jet printer which comprises the elastic member as setforth in the preceding item 14;

[0065] 19. A gasket integrated with a cover and is for an HDD whereinthe gasket for an HDD as set forth in the preceding item 4 is moldedintegrally with a cover.

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

[0066] The isobutylenic block copolymer which constitutes the resincomposition according to the present invention is composed ofisobutylenic polymer blocks and aromatic vinylic polymer blocks.

[0067] The blocks, which comprise isobutylene and an aromatic vinylcompound, respectively, may each a block wherein an other component iscopolymerized to the extent that the working effect of the presentinvention is not impaired thereby.

[0068] That is to say, the isobutylenic polymer blocks, which are each achain composed of isobutylene as a principal component, may be each acopolymer block of isobutylene and a cationic polymerizable monomerother than isobutylene.

[0069] None the less, it is preferable that the isobutylenic polymerblocks be each a block comprising at least 60% by weight of isobutyleneunit, particularly at least 80% by weight thereof. A content thereof ofless than 60% by weight leads to deterioration in the balance betweenthe physical properties and polymerization characteristics.

[0070] The cationic polymerizable monomer which is copolymerizable withisobutylene in the isobutylenic polymer blocks is exemplified, forinstance, by aliphatic olefins, dienes and vinyl ethers.

[0071] Likewise, the aromatic vinylic polymer blocks, which are each achain composed of an aromatic vinyl compound as a principal component,may be each a copolymer block of an aromatic vinyl compound and acationic polymerizable monomer other than an aromatic vinyl compound.

[0072] None the less, it is preferable that the aromatic vinylic polymerblocks be each a block comprising at least 60% by weight of an aromaticvinyl compound unit, particularly at least 80% by weight thereof. Acontent thereof of less than 60% by weight leads to deterioration in thebalance between the physical properties and polymerizationcharacteristics.

[0073] Examples of the aromatic vinyl compound include styrene, α-alkylsubstituted styrene such as α-methylstyrene; α-ethylstyrene; andα-methyl-p-methylstyrene, ring alkyl substituted styrene such aso-methylstyrene; m-methylstyrene; p-methylstyrene; 2,4-dimethylstyrene;ethylstyrene; 2,4,6-trimethylstyrene; o-t-butylstyrene;p-t-butylstyrene; and p-cyclohexylstyrene, ring halogenated styrene suchas o-chlorostyrene; m-chlorostyrene; p-chlorostyrene; and2-methyl-4-chlorostyrene, vinylnaphthalene derivative such as1-vinylnaphthalene, indene derivative, and divinylbenzene. Of these,styrene, α-methylstyrene and p-methylstyrene are preferable. Any of theabove-exemplified aromatic vinyl compound may be used alone or incombination with at least one other.

[0074] The cationic polymerizable monomer which is copolymerizable witharomatic vinyl compound in the isobutylenic polymer blocks isexemplified, for instance, by aliphatic olefins, dienes and vinylethers.

[0075] The ratio by weight of the isobutylenic polymer blocks in theisobutylenic block copolymer to the aromatic vinylic polymer blocks therein is preferably in the range of 60:40 to 80:20 from the viewpoint ofthe balance among the physical properties of the resin composition to beobtained.

[0076] It is possible in the resin composition according to the presentinvention to use any of styrenic, olefinic, urethane based and esterbased thermoplastic elastomers other than the isobutylenic blockcopolymer in combination therewith.

[0077] Examples of such thermoplastic elastomers include {circle over(1)} a block copolymer of crystalline polyethylene andethylene/butylene-styrene random copolymer, said polyethylene beingproduced by hydrogenating a block copolymer of polybutadiene andbutadiene-styrene random copolymer; {circle over (2)} a diblockcopolymer of crystalline polyethylene and polystyrene; a triblockcopolymer of styrene-ethylene/butylene-styrene (SEBS); a triblockcopolymer of styrene-ethylene/propylene-styrene (SEPS); especially blockcopolymer of styrene-ethylene/butylene-styrene; block copolymer ofstyrene-ethylene/propylene-styrene, each being produced by hydrogenatinga block copolymer of polybutadiene and polystyrene and a block copolymerof polyisoprene and polystyrene or a block copolymer of polybutadiene orethylene-butadiene random copolymer and polystyrene.

[0078] In the case where a thermoplastic elastomer other than theisobutylenic block copolymer is used in combination therewith, theamount of said thermoplastic elastomer to be used is preferably at most100 parts by weight based on 100 parts by weight of the isobutylenicblock copolymer. (In the following description, the simple wording“thermoplastic elastomer” means to include both the single use of theisobutylenic block copolymer and the simultaneous use thereof with athermoplastic elastomer other than the isobutylenic block copolymer).

[0079] The polyolefinic resin to be used in the resin compositionaccording to the present invention is not specifically limited, but canbe selected for use according to purpose of use and usage, and isexemplified by polyethylene, polypropylene, polybutene (especiallycrystalline polybutene) and the like. Among them, isotacticpolypropylene and a copolymer thereof are preferably usable, andparticularly those having a melt mass flow rate (MFR) of 0.1 to 50 g/10minutes, especially 0.5 to 30 g/10 minutes are preferably usable,wherein the MFR is measured in accordance with JIS K7210; 1999.

[0080] The polyolefin resin may contain so-called modified polyolefinresin, which is the resin produced by grafting an unsaturated carboxylicacid such as maleic acid, maleic anhydride, acrylic acid or an analogueor a polymerizable monomer bearing a hydroxy group onto theabove-mentioned polyolefin resin. Examples of usable modified polyolefinresin include those available on markets under the trade names “NuclelSeries” manufactured by Mitsui Dupont Polychemical Co.,Ltd.; “UmexSeries” manufactured by Sanyo Kasei Co.,Ltd.; “Exceller Series”manufactured by Exxon Chemical Co.,Ltd.; “Polydone Series” manufacturedby Uniroyal Co.,Ltd.; “Admer Series” manufactured by Mitsui ChemicalIndustries Co.,Ltd.; and the like.

[0081] The blending amount of the aforesaid polyolefin resin can bepreferably selected on at most 200 parts by weight based on 100 parts byweight of the thermoplastic elastomer. The blending amount thereof, whenexceeding 200 parts by weight based thereon, brings about liability tobleed out of a softening agent, thereby sometimes giving the cause fordeterioration in mechanical strength of the resin composition accordingto the present invention. In order to assure sufficient working effect,the blending amount thereof is preferably at least one part by weightbased thereon, more preferably at least 5 parts by weight. Taking intoconsideration the balance among various physical properties, theblending amount thereof is preferably at most 100 parts by weight basedthereon, more preferably at most 50 parts by weight.

[0082] The resin composition according to the present invention may beblended as desired, with polyphenylene ether for the purpose ofimproving the compression set thereof, The polyphenylene ether resin tobe used therefor may be selected for use from publicly well known ones,and is specifically exemplified by poly(2, 6-dimethyl-1, 4-phenyleneether); poly(2-methyl-6-ethyl-1, 4-phenylene ether); poly(2,6-diphenyl-1, 4-p henylene ether); poly(2-methyl-6-phenyl-1, 4-phenyleneether); and poly(2, 6-dichloro-1, 4-phenylene ether). There is alsousable a polyphenylene ether copolymer such as the copolymer of 2,6-dimethylphenol and a monohydric phenols(e.g. 2, 3, 6-trimethylpheno 1and 2-methyl-6-butylphenol). Of these are preferable poly(2, 6-dimethy1-1,4-phenylene ether) and the copolymer of 2, 6-dimethylphenol and 2,3, 6-trimethylphenol, and poly(2, 6-dimethyl- 1, 4-phenylene ether) ispreferable in particular.

[0083] The blending amount of the aforesaid polyphenylene ether can bepreferably selected on at most 100 parts by weight based on 100 parts byweight of the thermoplastic elastomer. The blending amount thereof, whenexceeding 100 parts by weight based thereon, unfavorably gives rise to afear of unreasonably high hardness of the thermoplastic elastomer. Inorder to assure sufficient working effect, the blending amount thereofis preferably at least one part by weight based thereon, more preferablyat least 5 parts by weight. Taking into consideration the balance amongvarious physical properties, the blending amount thereof is preferablyat most 75 parts by weight based thereon, more preferably at most 50parts by weight.

[0084] The resin composition according to the present invention may beblended with a non-aromatic rubber-softening agent for the purpose oflowering the hardness of the thermoplastic elastomer. From the viewpointof physical properties, the non-aromatic rubber-softening agent has aviscosity at 100° C. of preferably at most 5×10⁵ centipoise,particularly at most 1×10⁵ centipoise. From the viewpoint of molecularweight, the softening agent has a number average molecular weight of atmost 20,000, preferably at most 10,000, more preferably at most 5,000.In particular, such non-aromatic rubber-softening agent is preferablyany of paraffin base oil of mineral oil base, naphthene base oil andsynthetic polyisobutylene base oil each having a number averagemolecular weight in the range of 450 to 5,000. The softening agent maybe used alone or in combination with at least one other provided thatthey are favorably compatible with one another.

[0085] The blending amount of the aforesaid softening agent can bepreferably selected on at most 200 parts by weight based on 100 parts byweight of the thermoplastic elastomer. The blending amount thereof, whenexceeding 200 parts by weight based thereon, brings about liability tobleed out of a softening agent, thereby sometimes giving the cause fordeterioration in mechanical strength of the resin composition accordingto the present invention. In order to assure sufficient working effect,the blending amount thereof is preferably selected in theabove-mentioned range according to the molecular weight of thethermoplastic elastomer and the types of other components to be added tothe elastomer.

[0086] The resin composition according to the present invention may beblended with a petroleum base hydrocarbon resin for the purpose ofshifting a dielectric loss constant (tan 67) to the working temperatureregion of objective purpose of use and/or improving high lossproperties. Such petroleum base hydrocarbon resin is exemplified by anaromatic hydrocarbon resin, an aliphatic hydrocarbon resin and the like.The blending amount thereof is preferably in the range of 10 to 100parts by weight based on 100 parts by weight of the thermoplasticelastomer. The blending amount thereof, when being less than 10 parts byweight based thereon, sometimes results in that the working effect isnot sufficiently exhibited, whereas the amount, when being more than 100parts by weight based thereon, sometimes brings about unreasonably largecreep, thus making the resin molded article unusable owing to excessivedeformation.

[0087] In addition thereto, the resin composition according to thepresent invention may be blended with an inorganic filler such as clay,diatomaceous earth, silica, talc, barium sulfate, calcium carbonate,magnesium carbonate, a metal oxide, mica, graphite and aluminumhydroxide, various metal powders, glass powder, ceramics powder,granular or powdery solid filler such as granular or powdery polymer,and a variety of natural or artificial short fibers and long fibers(such as a variety of polymer fibers). The inorganic filler ispreferably in the form of flake.

[0088] Moreover, the resin composition according to the presentinvention may be incorporated inside with bubbles, which is directed tolightweightness.

[0089] A method for incorporating bubbles is not specifically limited,but is exemplified by a method in which an inorganic hollow filler suchas glass balloon and silica balloon, or an organic hollow filler such aspolyfluorinated vinylidene and polyfluorinated vinylidene copolymer isblended; a method in which any of various foaming agents is mixed; amethod in which a gas is mechanically incorporated upon mixing; and thelike method.

[0090] It is possible at need to use simultaneously with thecomposition, such additive as flame retardants, antimicrobial agents,hindered a mine base light stabilizer, ultraviolet rays absorbers,antioxidants, colorants, silicone oil, silicone polymer, coumaroneresin, coumarone indene resin, phenol terpene resin, petroleum basehydrocarbon, various tackifying agent such as rosin derivative, variousadhesive elastomer such as Rheostomer B (trade name, manufactured byRiken Vinyl Co.,Ltd.) and the like.

[0091] The process for producing the resin composition according to thepresent invention is not specifically limited, but well known processesare applicable thereto.

[0092] For instance, the resin composition is readily producible by aprocess which comprises the steps of melt kneading each of theabove-mentioned components and the additive components to be used asdesired by the use of a heating kneader such as a single screw extruder,a twin screw extruder, a roll, a Banbury mixer, a Brabender, a kneaderand a high shear type mixer; further adding as desired to the resultantmixture, a cross-linking agent such as an organic peroxide, across-linking aid or the like, or simultaneously mixing with thenecessary components; and melt kneading by heating the resultantmixture.

[0093] It is also possible to produce the resin composition by preparingin advance, a resin composition in which a high molecular organicmaterial and a softening agent have been kneaded, and mixing thecomposition thus prepared with at least one high molecular organicmaterial whose type is same as or different from that used here.

[0094] Further, the resin composition according to the present inventioncan be cross-linked by adding thereto, a cross-linking agent such as anorganic peroxide, a cross-linking aid and the like.

[0095] As described hereinbefore, the resin composition according to thepresent invention is particularly well suited for constituting anelastic member for an ink jet printer, an insulator for a recordingmedium drive, a gasket for an HDD and an impact absorbing material foran HDD.

[0096] As a consequence, the elastic member for an ink jet printer,insulator for a recording medium drive, gasket for an HDD and impactabsorbing material for an HDD according to the present invention haveovercome and eliminated the problems as described hereinabove.

[0097] The elastic member according to the present invention which isfor an ink jet printer and which is constituted of the resin compositionaccording to the present invention is favorably used for an ink tank inan ink jet printer which tank comprises an ink chamber filled in withink and an ink supply portion supplying a recording head with ink.

[0098] The elastic member is not specifically limited provided that itis a part item requiring an elastic member in the aforesaid ink tank,and thus is usable for any of part items. It is favorable in particularto use the same in an ink jet printer as an ink tank valve that isinstalled at a position where an ink chamber and an ink supply portionare separated from each other, is moved by the pressure differencetherebetween, and supplies a recording head portion with ink filled inthe ink chamber, also as a sealing member that is installed at an inksupply port, and prevents ink from leaking through said port.

[0099] By applying to the elastic member, the resin compositionaccording to the present invention which contains the isobutylenic blockcopolymer, the working effect is exhibited as described hereunder.

[0100] The above-mentioned ink tank valve is, for instance, of such astructure that an elastic member is integrally formed on the surface ofa plastic-made substrate, and in the case of producing a molded articlehaving such structure it is advantageous to adopt injection moldingmethod by means of two-color molding which method is simple inproduction process and low in production cost. Although thethermosetting rubber which has hitherto been used as the aforesaidelastic member is difficult to produce by two-color molding with aplastic, the use of the material comprising the isobutylenic blockcopolymer according to the present invention facilitates two-colormolding thus enabling to produce the ink tank valve at a low cost.

[0101] Moreover although it has been difficult for the conventionalthermosetting rubber to mold and vulcanize a low hardness material intoa member having a desirable form, the use of the material comprising theisobutylenic block copolymer according to the present inventionsurmounts the difficulty, thus enabling to produce a molded articlehaving moderate elasticity and excellent mechanical and physicalproperties.

[0102] Further it is made possible by the present invention to use aliquid such as paraffin base oil having polarity much different fromthat of ink, as an oil component to be used in the case of lowering thehardness of a thermoplastic elastomer such as isobutylenic blockcopolymer in the resin composition and besides, the oil is less liableto be compatible with styrene block which is an aggregation domain ofthe isobutylenic block copolymer, thus exerting less influence on thephysical properties such as the strength of the elastomer.

[0103] Still further it is made possible by the use of the thermoplasticelastomer comprising the isobutylenic block copolymer to obtain an inktank valve which is minimized in change including swelling due to asolvent such as ink and is excellent in durability; a sealing member foran ink tank; a sealing member for preventing ink from leaking through arecording head; and the like.

[0104] The sealing member according to the present invention not onlycan be installed at an ink supply port, but also can be used at ajunction connecting between an ink supply portion and a recording head.

[0105] The ink tank according to the present invention is notspecifically limited provided that the above-mentioned elastic member isused therefor. It may be packed with a foam such as polyurethane foam tohold ink, or may not be packed with a foam.

[0106] The shapes of the aforesaid ink tank valve and the sealing memberfor the ink tank are not specifically limited, but are exemplified bythe shapes same as those having heretofore been used in ink tanks. Asmethods for the production thereof, for instance in the case of thesealing member for the ink tank, there are adoptable publicly well knownmethods including injection molding, extrusion molding and the like. Inthe case of the ink tank valve, a two-color molding method is adoptablewhich comprises melt injection molding plastics as a base material intoa mold, and subsequently melt injection molding the resin compositionaccording to the present invention thereon to integrally laminate theresin composition on the surface of the molded plastics article.Alternatively, an insert molding method is also adoptable whichcomprises melt injection molding plastics into a mold, subsequentlyinserting the resultant molded article into an other mold, and meltinjection molding the resin composition according to the presentinvention thereon to integrally laminate the resin composition on thesurface of the molded plastics article.

[0107] The insulator for a recording medium drive according to thepresent invention is produced by molding the resin composition accordingto the present invention into a desirable form by a well known methodsuch as injection molding. The insulator is favorably usable foracoustic equipment, information-related equipment, information transferequipment, game-related equipment and the like, more specifically, CDplayer, insulator for car mounted CD, insulators for hard disc drive andfloppy disc drive, various personal computer, insulators for CD-ROM usedin domestic game equipment and various instruments.

[0108] The gasket for an HDD according to the present invention isproduced by molding the resin composition according to the presentinvention into a desirable form by a well known method such as injectionmolding. It is used as a gasket, a gasket integrated with a cover byintegrally molding the same with a cover.

[0109] As the cover in a gasket integrated with a cover, there is usablea rigid resin cover, but a metallic cover is preferable fromprocessability and the like. The metal to be used is not specificallylimited, but may be properly optionally selected for use from coldrolled steel sheets, galvanized steel sheets, aluminum/zinc alloy platedsteel sheets, stainless steel sheets, aluminum sheets, aluminum alloysheets, magnesium sheets and magnesium alloy sheets. Injection moldedmagnesium sheets are also usable. There are preferably usable metallicsheets which are treated with non-electrolytic nickel plating for itsexcellent corrosion resistance. As a method for non-electrolytic nickelplating, there is usable any of publicly well known methods that haveheretofore been applied to metallic raw materials, for instance, amethod which comprises immersing a metallic sheet to be treated in anon-electrolytic nickel plating bath comprising an aqueous solution at apH of approximately 4.0 to 5.0 and at a temperature of approximately 85to 95° C. which contains nickel sulfate, sodium hypochlorite, lacticacid, propionic acid and the like each in a proper proportion. Thethickness of the cover, which is properly optionally selected, is in therange of usually 0.3 to 1.0 mm, preferably 0.4 to 0.6 mm.

[0110] The impact absorbing material for a HDD according to the presentinvention is produced by molding the resin composition according to thepresent invention into a desirable form by a well known method such asinjection molding, and is used, for instance, as a crush stop.

[0111] In this connection, priority is claimed by the present patentapplication on the basis of Japanese Patent Application Nos. 290810/2001(Hei 13), 290811/2001, 290812/2001, 290813/2001 and 290810/2001, thecitations of which are made by the present application in whole.

[0112] In what follows, the present invention will be described in moredetail with reference to working examples, which however shall neverlimit the present invention thereto.

[0113] Evaluations were made of the physical properties in the followingworking examples, comparative examples and reference examples by themethods as described hereunder.

[0114] (1) Hardness

[0115] Hardness was measured in accordance with JIS K 6301-1993, and themeasurement results were indicated in terms of relative value based on100 as the relative hardness in Comparative Example 1.

[0116] (2) tan δ

[0117] Dielectric loss tangent tan δ was measured at 25° C., 15 Hz, 1%strain, and the measurement results were indicated in terms of relativevalue based on 100 as the relative tan δ in Comparative Example 1.

[0118] (3) Injection Moldability

[0119] Injection moldability was evaluated by two marks including ◯;moldable within an accuracy of ±1%, x; non-moldable.

[0120] (4) Oil Bleed Property

[0121] Oil bleed property was evaluated by immersing elastic memberspecimen in ink, and the specimen was checked for bleed out at 70° C.for 24 hours.

[0122] (5) Sealability

[0123] Sealability was evaluated by installing a sealing member specimenprepared under preparation conditions of mold temperature of 80° C. andresin temperature of 70° C. on an ink tank, applying it to an ink jetprinter for use at 25° C. for one month, and checking the same forleakage therethrough.

[0124] (6) Vibration Absorbing Property

[0125] Vibration absorbing property was evaluated by incorporating aninsulator specimen prepared from the resin composition in a marketedCD-ROM startup apparatus, operating the apparatus, and measuring thevibration transmission factor onto the installation floor, and themeasurement results were indicated in terms of relative value based on100 as the vibration transmission factor in Comparative Example 1.

[0126] (7) Amount of Gas Generation

[0127] Amount of gas generated from 10 mg of the resin composition at150° C. for 20 minutes was measured by the use of a GC-MS, and themeasurement results were indicated in terms of relative value based on100 as the relative amount of gas generation in Comparative Examples 7and 9 (same blending proportion).

[0128] (8) Gas permeability

[0129] Gas permeability was evaluated by measuring permeation rate ofcyclic dimethylsiloxane (D4) at 60° C. for 24 hours through a sheet madeof the resin composition measuring 2 mm in thickness and 5 cm square,and the measurement results were indicated in terms of relative valuebased on 100 as the relative amount of gas permeability in ComparativeExample 7.

[0130] (9) Impact Absorbing Property

[0131] An iron ball with one kg of weight was dropped onto a sheet madeof the resin composition measuring 2 mm in thickness and 5 cm squarefrom a position at a height of one meter, and the rebound height of theball was measured to evaluate the impact absorbing property by two marksincluding x; 2 cm or more (including unmeasurable case), and ◯; lessthan 2 cm.

[0132] The blending raw materials in the following working examples,comparative examples and reference examples are each describedhereunder.

[0133] Polymer A: styrene-isobutene-styrene block copolymer (styrenecontent: 30% by weight)

[0134] Polymer B: styrene-ethylene/butylene-styrene block copolymer(manufactured by Krayton Polymer Co.,Ltd. under the trade name “kraytonG 16 50”, styrene content: 30% by weight)

[0135] Polymer C: polypropylene (manufactured by Chisso Corporationunder the trade name “Polypro CF 3031”)

[0136] Polymer D: modified polyphenylene ether (manufactured by AsahiChemical Industry Co.,Ltd., under the trade name “Zailon X 0108 ”).

[0137] Polymer E: aromatic petroleum based hydrocarbon resin(manufactured by Shin-Nippon Oil Co.,Ltd., under the trade name “NissekiNeopolymer 120”).

[0138] Polymer F: uretahne rubber (manufactured by Kuraray Co.,Ltd.,under the trade name “Kuramiron U”)

[0139] Oil A: liquid polybutene (manufactured by Nisseki ChemicalCo.,Ltd., under the trade name “HV 100”)

[0140] Oil B: paraffin base oil (manufactured by Mitsui ChemicalCo.,Ltd., under the trade name “Lucant HC-150”)

[0141] Oil C: paraffin base oil (manufactured by Idemitsu KosanCo.,Ltd., under the trade name “Diana Process Oil PW 380”)

EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 AND 2

[0142] Samples of resin compositions were prepared by sufficientlykneading each of the components having blending composition as given onTable 1, and the physical properties thereof were evaluated. As theresults, as is clear from Table 1, the resin compositions in Examples 1to 5 are excellent in low hardness, high loss properties (vibrationabsorption properties) and further in injection moldability, and haveeach low gas permeability, thus enabling injection molding with stabledimensional accuracy. TABLE 1 Comparative Example Example 1 2 3 4 5 1 2BLENDUG PROPRTION (parts by weight) Polymer A 100 100 100 100 50 100Polymer B 50 100 Polymer C 15 15 15 7.5 7.5 15 Polymer D 7.5 7.5 Oil A150 150 7.5 150 150 Oil B 150 Oil C 150 75 EVALUATION hardness 60 60 6070 70 100 85 Tan δ 10 8 6 6 5 1 1.2 Injection moldability ◯ ◯ ◯ ◯ ◯ ◯ X

EXAMPLES 6 TO 10 AND COMPARATIVE EXAMPLES 3 AND 4

[0143] Samples of resin compositions were prepared by sufficientlykneading each of the components having blending composition as given onTable 2, and evaluations were made of the physical properties (oil bleedproperties and sealing properties) thereof that were required of theelastic member for an ink jet printer.

[0144] As the results, as is clear from Table 2, no oil bleed norleakage through a seal was observed in the resin compositions inExamples 6 to 10, while both oil bleed and leakage through a seal wereobserved in the resin compositions in Comparative Examples. TABLE 2Comparative Example Example 6 7 8 9 10 3 4 BLENDUG PROPRTION (parts byweight) Polymer A 100 100 100 50 50 Polymer B 50 50 100 100 Polymer C 1515 15 15 15 15 15 Polymer D 5 10 15 15 15 15 Oil A 150 75 7.5 150 Oil B150 75 150 Oil C 150 75 EVALUATION Oil bleed properties none none nonenone none yes yes Seal leakage none none none none none yes yes

EXAMPLES 11 TO 16 AND COMPARATIVE EXAMPLES 5 AND 6

[0145] Samples of resin compositions were prepared by sufficientlykneading each of the components having blending composition as given onTable 3, and evaluations were made of the physical properties (oil bleedproperties and vibration absorption properties: vibration absorptivity)thereof that were required of the insulator for an recording mediumdrive.

[0146] As the results, as is clear from Table 3, in the resincompositions in Examples 11 to 16 no oil bleed was observed andvibration absorption properties were superior to those of ComparativeExamples, while oil bleed was observed in the resin compositions inComparative Examples. TABLE 3 Comparative Example Example 11 12 13 14 1516 5 6 BLENDUG PROPRTION (parts by weight) Polymer A 100 100 100 50 50100 Polymer B 50 50 100 100 Polymer C 15 15 15 15 15 15 15 Polymer D 510 15 15 15 15 Polymer E 50 150 Oil A 150 75 75 150 Oil B 120 75 150 OilC 100 75 100 EVALUATION Oil bleed properties none none none none nonenone yes yes Vibration absorbing property 45 40 50 75 75 35 100 100

EXAMPLES 17 TO 21 AND COMPARATIVE EXAMPLES 7 AND 8

[0147] Samples of resin compositions were prepared by sufficientlykneading each of the components having blending composition as given onTable 4, and evaluations were made of the physical properties (amount ofgas generation/gas permeability) thereof that were required of thegasket for an HDD.

[0148] As the results, as is clear from Table 4, in the resincompositions in Examples 17 to 21 there were observed low gas generationand low gas permeability more excellent than those in ComparativeExample 7 (urethane rubber). TABLE 4 Comparative Example Example 17 1819 20 21 7 8 BLENDUG PROPRTION (parts by weight) Polymer A 100 100 10050 50 Polymer B 50 50 100 Polymer C 15 15 15 15 15 15 Polymer D 5 10 1515 15 Polymer F 100 Oil A 150 75 75 Oil B 150 75 150 EVALUATION Amountof gas 30 20 25 25 25 100 30 generation Gas permeability 10 10 10 75 75100 100

EXAMPLES 22 to 26 AND COMPARATIVE EXAMPLES 9 AND 10

[0149] Samples of resin compositions were prepared by sufficientlykneading each of the components having blending composition as given onTable 5, and evaluations were made of the physical properties (amount ofgas generation and impact absorbing properties) thereof that wererequired of the impact absorbing material for an HDD.

[0150] As the results, as is clear from Table 5, in the resincompositions in Examples 22 to 26 there were observed low gas generationand high impact absorbing properties more excellent than those inComparative Example 9 (urethane rubber ). TABLE 5 Comparative ExampleExample 22 23 24 25 26 9 10 BLENDUG PROPRTION (parts by weight) PolymerA 100 100 100 50 50 Polymer B 50 50 100 Polymer C 15 15 15 15 15 15Polymer D 5 10 15 15 15 Polymer F 100 Oil A 150 75 75 Oil B 150 75 150EVALUATION Amount of gas 50 40 50 50 40 100 50 generation Impactabsorbing ◯ ◯ ◯ ◯ ◯ ◯ X property

INDUSTRIAL APPLICABILITY

[0151] According the present invention, it is made possible to provide aresin composition which has a low hardness, is favorable in high lossproperties (vibration absorbing properties) and gas permeationresistance, and is excellent in injection moldability, thereby enablingitself to be injection molded with stable dimensional accuracy. Thisresin composition according to the present invention is particularlysuitable for constituting an elastic member for an ink jet printer, aninsulator for a recording medium drive, a gasket for an HDD and animpact absorbing material for an HDD.

[0152] The elastic member for an ink jet printer according to thepresent invention enables itself to be injection molded by means oftwo-color molding with plastics; has sealing properties comparable tothose of isobutylene; is excellent in sealing properties and oil bleedproperties even with a comparatively small amount of added oil and lowhardness; is favorably used in particular in an ink jet printer as anink tank valve that is installed at a position where an ink chamber andan ink supply portion are separated from each other, is moved by thepressure difference therebetween, and supplies a recording head portionwith ink filled in the ink chamber, also as a sealing member that isinstalled at an ink supply port, and prevents ink from leaking throughsaid port, or as a sealing member that is installed on the main body ofthe ink jet printer, and prevents ink from leaking through the recordinghead; and further is effectively usable as a sealing member for ajunction or the like which connects an ink supply portion and arecording head.

[0153] The insulator for a recording medium drive according to thepresent invention exhibits such working effects as being excellent invibration absorbing properties of lightweight articles, particularly invibration absorbing properties in a low frequency region and indurability by virtue of the use of materials characterized by high lossproperties (vibration absorbing properties), favorable oilpreservability, low hardness, low compression set and the like.

[0154] The gasket for an HDD according to the present invention, whichis favorable in gastihgtness and resistance to penetration andpermeation of substances and which is minimized in the generation ofharmful gases, is particularly well suited for a hard disc drive.

[0155] The impact absorbing material according to the present invention,which is minimized in the amount of gas generation and which hassufficiently high impact absorbing properties, is favorably usable as acrush stopper which is minimized in the displacement due to the impactfrom a stopper arm.

1. A resin composition which comprises 100 parts by weight of athermoplastic elastomer containing an isobutylenic block copolymercomposed of isobutylenic polymer blocks and aromatic vinylic polymerblocks, and 1 to 50 parts by weight of a polyolefin resin.
 2. An elasticmember which is for an ink jet printer and which is constituted of theresin composition as set forth in claim
 1. 3. An insulator which is fora recording medium drive and which is constituted of the resincomposition as set forth in claim
 1. 4. A gasket which is for an HDD andwhich is constituted of the resin composition as set forth in claim 1.5. An impact absorbing material which is for an HDD and which isconstituted of the resin composition as set forth in claim
 1. 6. Theresin composition according to claim 1 wherein an aromatic vinyliccompound which constitutes the aromatic vinylic polymer blocks is atleast one species selected from the group consisting of styrene,α-methylstyrene and p-methylstyrene.
 7. The resin composition accordingto claim 1 wherein the ratio by weight of the isobutylenic polymerblocks in the isobutylenic block copolymer to the aromatic vinylicpolymer blocks therein is in the range of 60:40 to 80:20.
 8. The resincomposition according to claim 1 wherein the polyolefin resin isisotactic polypropylene or a copolymer thereof.
 9. The resin compositionaccording to claim 1 wherein the polyolefin resin is modifiedpolyolefin.
 10. The resin composition according to claim 1 wherein thethermoplastic elastomer containing an isobutylenic block copolymercontains a thermoplastic elastomer other than said elastomer in additionto said isobutylenic block copolymer.
 11. The resin compositionaccording to claim 1 which further comprises at most 100 parts by weightof polyphenylene ether based on 100 parts by weight of the thermoplasticelastomer containing an isobutylenic block copolymer composed ofisobutylenic polymer blocks and aromatic vinylic polymer blocks.
 12. Theresin composition according to claim 1 which further comprises at most200 parts by weight of a non-aromatic softening agent for rubber basedon 100 parts by weight of the thermoplastic elastomer containing anisobutylenic block copolymer composed of isobutylenic polymer blocks andaromatic vinylic polymer blocks.
 13. The resin composition according toclaim 1 which further comprises 10 to 100 parts by weight of a petroleumbase hydrocarbon resin based on 100 parts by weight of the thermoplasticelastomer containing an isobutylenic block copolymer composed ofisobutylenic polymer blocks and aromatic vinylic polymer blocks.
 14. Theelastic member for an ink jet printer according to claim 2 which isinstalled on the main body of said ink jet printer, and is used as asealing member.
 15. An ink tank which comprises the elastic member asset forth in claim
 2. 16. An ink tank which comprises the elastic memberas set forth in claim
 14. 17. An ink jet printer which comprises theelastic member as set forth in claim
 2. 18. An ink jet printer whichcomprises the elastic member as set forth in claim
 14. 19. A gasketwhich is integrated with a cover and is for an HDD wherein the gasketfor an HDD as set forth in claim 4 is molded integrally with a cover.